The invention relates to an intercalation compound comprising vanadium, phosphorus and oxygen as primary components with monohydric alcohol being intercalated between layers of the compound and to a vanadium phosphorus mixed oxide as well as to processes for preparing the same.
As a layered compound comprising vanadium, phosphorus and oxygen as primary components, vanadyl phosphate, vanadyl hydrogen phosphate hemihydrate or the like is known. Here, vanadyl hydrogen phosphate hemihydrate, VOHOP4.0.5H2O, is well known as a precursor for divanadyl pyrophosphate, [(VO)2P2O7], which is used as a catalyst for the preparation of maleic anhydride by oxidizing butane.
It is known that an organic compound is intercalated between layers of these layered compounds to give a substance with a widened space between the layers. For example, a substance intercalated with pyridine or pyrrole is disclosed in Inorg. Chem. 21, 3820 (1982) and Chem. Lett. 31 (1993).
U.S. Pat. No. 4,418,003 disclosed a process for the manufacture of a phosphorus vanadium catalyst suitable for use in the manufacture of maleic anhydride from butane, which process comprises reacting P2O3 in an aliphatic alcohol having 1 to 8 carbon atoms to produce mixed phosphate esters and reacting a vanadium compound with an inorganic acid in the aliphatic alcohol to prepare acidified alcohol and a vanadium ester, and using these to produce a vanadium phosphorus oxide catalyst which is dissolved in the acidified alcohol. The inter-layer space of the catalyst produced is 8.75 xc3x85, which is larger than that of vanadyl hydrogen phosphate hemihydrate, 5.4 xc3x85. This suggest that methanol is intercalated between the layers.
Vanadium-phosphorus mixed oxide is widely known as a catalyst or as a precursor thereof for the manufacture of maleic anhydride by oxidizing butane. Generally, vanadium-phosphorus mixed oxide is prepared by calcining vanadyl phosphate or vanadyl hydrogen phosphate hemihydrate, comprising vanadium, phosphorus and oxygen as primary components, in a nitrogen atmosphere or a reactive atmosphere comprising butane, nitrogen and oxygen at 350xc2x0 C. to 700xc2x0 C. The vanadium-phosphorus mixed oxide thus obtained has a relatively small surface area of from 10 to 50 m2/g.
To prepare a catalyst of higher activity, some studies have been made to increase a surface area of vanadium-phosphorus mixed oxide. Catal. Today 16, 113 (1993) describes a method where vanadyl hydrogen phosphate hemihydrate is mixed with water or lower alcohol and then calcined to obtain a larger surface area of the calcined product. However, the surface area of the resultant calcined product is at most about 64 m2/g. Appl. Catal. 154, 103 (1997) describes a method where vanadyl hydrogen phosphate hemihydrate is crashed to powder with a ball mill to obtain a larger surface area of the calcined product. However, the surface area of the resultant calcined product is at most about 46 m2/g. In either method, the surface area of the resultant calcined product is not satisfactory for a catalyst for preparing maleic anhydride.
For producing a vanadium-phosphorus mixed oxide having meso-micropores, Chem. Mater., 7,1429 (1995) discloses a method of synthesizing a meso structure material having a hexagonal structure comprising vanadium and phosphorus by using alkyltrimethylammonium chloride as a template agent, wherein alkyl group has 12 to 16 carbon atoms. It mentions nothing about a surface area of the vanadium-phosphorus mixed oxide.
Japanese Patent Application Laid-open H8-259208 discloses an intercalation compound and a method of preparing the same, in which compound diols are intercalated between layers of a layered compound comprising vanadium, phosphorus and oxygen as primary components. There, monohydric alcohols are not intercalated. As shown in its Comparative Example, isobutyl alcohol, which is a monohydric alcohol, cannot be intercalated between layers of the layered compound comprising vanadium, phosphorus and oxygen as primary components in that method.
WO 98/15353 discloses an intercalation compound and a method of preparing the same, in which compound an aliphatic primary monohydric alcohol is intercalated between layers of a layered compound comprising vanadium, phosphorus and oxygen as primary components. In the method, V2O5, P2O5 and the aliphatic primary monohydric alcohol are reacted in atmospheric pressure. The method is to intercalate an aliphatic primary monohydric alcohol, and accordingly, nothing is described about intercalation of an alicyclic monohydric alcohol or an aromatic monohydric alcohol. In the Comparative Examples, it is mentioned that secondary alcohols and tertiary alcohols cannot be intercalated. Further, an extremely long time is required to intercalate aliphatic primary monohydric alcohol. For example, in Example 1, 455 hours were required for intercalating methanol. In order to intercalate a branched aliphatic primary monohydric alcohol, it is suggested that it is necessary to use a more concentrated phosphoric acid to increase a rate of the reaction. However, by the method, a compound with a sufficient amount of intercalated branched aliphatic primary monohydric alcohol was not obtained, judging from a small intensity of the X-ray diffraction pattern showing intercalation of the branched aliphatic primary monohydric alcohol.
The purpose of the present invention is to provide a novel intercalation compound in which an aliphatic secondary monohydric alcohol, an alicyclic monohydric alcohol, or an aromatic monohydric alcohol is intercalated between the layers of a compound comprising vanadium, phosphorus and oxygen as primary components.
Another purpose of the present invention is to provide a novel method for quickly and conveniently preparing an intercalation compound in which a monohydric alcohol is intercalated between a layered compound comprising vanadium, phosphorus and oxygen as primary components.
Still another purpose of the present invention is to provide a novel vanadium-phosphorus mixed oxide having a remarkably large surface area and a method of preparing the same.
The present inventors have made intensive researches for a method of intercalating various kinds of monohydric alcohols between layers of a layered compound comprising vanadium, phosphorus and oxygen as primary components. As a result, it has been found that by reacting vanadium oxide having a valence of vanadium in a range of at least 4 to less than 5, phosphorus pentoxide and monohydric alcohol in atmospheric pressure, or by reacting vanadium oxide having a valence of vanadium in a range of at least 4 to at most 5, phosphorus pentoxide and a monohydric alcohol under pressure, the monohydric alcohol can be intercalated between layers of the layered compound comprising vanadium, phosphorus and oxygen as primary components, which cannot be attained by the method described in JPA Laid-open H8-259208. Also it has been found that aliphatic secondary monohydric alcohols, alicyclic monohydric alcohols or aromatic monohydric alcohols as well as aliphatic primary monohydric alcohols can be intercalated quickly and conveniently between layers of the layered compound comprising vanadium, phosphorus and oxygen as primary components, which cannot be attained by the method described in WO 98/15353.
Thus, the present invention is (1) an intercalation compound in which monohydric alcohol is intercalated between layers of a layered compound comprising vanadium, phosphorus and oxygen as primary components, characterized in that the monohydric alcohol is aliphatic secondary monohydric alcohol, alicyclic monohydric alcohol, or aromatic monohydric alcohol.
Preferred embodiments of the present invention are as follows. (2) The intercalation compound described in (1) above, wherein the compound has a structure where a part or the whole of a moiety, POH, present in a layered compound, vanadyl hydrogen phosphate hemihydrate represented by (VO) (HOP)O3. 0.5H2), is replaced with a moiety, POR, of phosphoric acid ester of the aliphatic secondary monohydric alcohol, the alicyclic monohydric alcohol, or the aromatic monohydric alcohol, wherein R represents the residue of the monohydric alcohol, and a part or the whole of the H2O present in said compound is replaced with the aliphatic secondary monohydric alcohol, the alicyclic monohydric alcohol, or the aromatic monohydric alcohol.
(3) The intercalation compound described in (1) or (2) above, wherein the aliphatic secondary monohydric alcohol has 3 to 8 carbon atoms.
(4) The intercalation compound described in (1) or (2) above, wherein the aliphatic secondary monohydric alcohol is selected from the group consisting of 2-propanol, 2-butanol, 2-pentanol, 2-hextanol, 2-heptanol, and 2-octanol.
(5) The intercalation compound described in (1) or (2) above, wherein the alicyclic monohydric alcohols has 5 to 8 carbon atoms.
(6) The intercalation compound described in (1) or (2) above, wherein the alicyclic monohydric alcohols is selected from the group consisting of cyclopentanol, cyclohexanol, 4-methylcyclohexanol, 3-methylcyclopentanol, and 3-ethylcyclopentanol.
(7) The intercalation compound described in (1) or (2) above, wherein the aromatic monohydric alcohols has 7 to 12 carbon atoms.
(8) The intercalation compound described in (1) or (2) above, wherein the aromatic monohydric alcohols is selected from the group consisting of benzyl alcohol and 2-phenylethylalcohol.
(9) The intercalation compound described in any one of (1) to (4) above, wherein the inter-layer space of the intercalation compound in which aliphatic secondary monohydric alcohol is intercalated is in the range of from 10 to 15 xc3x85.
(10) The intercalation compound described in any one of (1), (2), (5) or (6) above, wherein the inter-layer space of the intercalation compound in which alicyclic monohydric alcohol is intercalated is in the range of from 10 to 15 xc3x85.
(11) The intercalation compound described in any one of (1), (2), (7) or (8) above, wherein the inter-layer space of the intercalation compound in which aromatic monohydric alcohol is intercalated is in the range of from 15 to 25 xc3x85.
The aforesaid intercalation compound in which aliphatic secondary monohydric alcohol, alicyclic monohydric alcohol, or aromatic monohydric alcohol is intercalated may be prepared by the present method described below. By the present method, aliphatic primary monohydric alcohols as well as aliphatic secondary monohydric alcohols, alicyclic monohydric alcohols or aromatic monohydric alcohols can be intercalated between layers quickly and conveniently.
Thus the present method is (12) a method of preparing an intercalation compound in which monohydric alcohol is intercalated between layers of a layered compound comprising vanadium, phosphorus and oxygen as primary components, characterized in that vanadium with a valence of vanadium in a range of from at least 4 to less than 5, phosphorus pentoxide and monohydric alcohol are reacted with one another in atmospheric pressure.
Preferred embodiments of the above invention are as follows.
(13) The method in (12) above, wherein the valence of vanadium is 4.5.
(14) The method described in (12) or (13) above, wherein the vanadium oxide is V4O9.
(15) A method of preparing an intercalation compound in which monohydric alcohol is intercalated between layers of a layered compound comprising vanadium, phosphorus and oxygen as primary components, characterized in that vanadium compound with a valence of vanadium of 5 is reduced in alcohol or aldehyde into vanadium oxide with a valence of vanadium in a range of from at least 4 to less than 5, and the vanadium oxide is isolated, and then mixed into monohydric alcohol, to which mixture phosphorus pentoxide is added and heated.
(16) A method of preparing an intercalation compound in which monohydric alcohol is intercalated between layers of a layered compound comprising vanadium, phosphorus and oxygen as primary components, characterized in that vanadium compound with a valence of vanadium of 5 is reduced in alcohol or aldehyde into vanadium oxide with a valence of vanadium in a range of from at least 4 to less than 5, and the vanadium oxide is isolated, and then added to a reaction product of monohydric alcohol with phosphorus pentoxide and heated.
(17) A method of preparing an intercalation compound in which monohydric alcohol is intercalated between layers of a layered compound comprising vanadium, phosphorus and oxygen as primary components, characterized in that vanadium compound with a valence of vanadium of 5 is reduced in alcohol or aldehyde into vanadium oxide with a valence of vanadium in a range of from at least 4 to less than 5, to which monohydric alcohol and phosphorus pentoxide are added and heated.
(18) The method described in any one of (15) to (17) above, wherein the vanadium compound with a valence of vanadium of 5 is vanadium pentoxide.
(19) The method described in any one of (12) to (18) above, wherein the monohydric alcohol is selected from aliphatic primary monohydric alcohols having 1 to 12 carbon atoms, aliphatic secondary monohydric alcohols having 3 to 8 carbon atoms, alicyclic monohydric alcohols having 5 to 8 carbon atoms, and aromatic monohydric alcohols having 7 to 12 carbon atoms.
(20) The method described in (19) above, wherein the aliphatic primary monoydric alcohol is selected from the group consisting of methanol, ethanol, 1-propanol, 1-butanol, isobutanol, isopentanol, neopentanol, 2-methyl-1-butanol, 1-pentanol, 1-hexanol, and 1-octanol, the aliphatic secondary monoydric alcohol is selected from the group consisting of 2-propanol, 2-butanol, 2-pentanol, 2-hexanol, 2-heptanol, and 2-octanol, the alicyclic monohydric alcohol is selected from the group consisting of cyclopentanol, cyclohexanol, 4-methylcyclohexanol, 3-methylcyclopentanol, and 3-ethylcyclopentanol and the aromatic monohydric alcohol is selected from the group consisting of benzyl alcohol and 2-phenylethylalcohol.
(21) The method described in any one of (12) to (20) above, wherein the intercalation compound in which monohydric alcohol is intercalated between layers of a layered compound comprising vanadium, phosphorus and oxygen as primary components has a structure where a part or the whole of a moiety, POH, present in a layered compound, vanadyl hydrogen phosphate hemihydrate represented by (VO) (HOP)O3. 0.5H2O, is replaced with a moiety, POR, of phosphoric acid ester of the aliphaticmonohydric alcohol, wherein R represents the residue of the aliphatic monohydric alcohol, and a part or the whole of the H2O present in said layered compound is replaced with the aliphatic monohydric alcohol.
Further, the present inventors have found that, in the aforesaid present method, the intercalation compound can be prepared in a shorter time by carrying out a reaction preferably under pressure and vanadium oxide with a valance of vanadium of 5 can be used.
Thus, the present method is (22) a method of preparing an intercalation compound in which monohydric alcohol is intercalated between layers of a layered compound comprising vanadium, phosphorus and oxygen as primary components, characterized in that vanadium oxide with a valence of vanadium in a range of from at least 4 to at most 5, phosphorus pentoxide and monohydric alcohol are reacted with one another under pressure.
Preferred embodiments of the aforesaid method are as follows.
(23) The method described in (22) above, wherein the valence of vanadium is in a range of from 4 to less than 5.
(24) The method described in (22) above, wherein the valence of vanadium is 4.5.
(25) The method described in (22) above, wherein the vanadium oxide is V4O9.
(26) The method described in (22) above, wherein the vanadium compound with a valence of vanadium of 5 is vanadium pentoxide.
(27) The method described in any one of (22) to (26) above, wherein the monohydric alcohol is selected from aliphatic primary monohydric alcohols having 1 to 12 carbon atoms, aliphatic secondary monohydric alcohols having 3 to 8 carbon atoms, alicyclic monohydric alcohols having 5 to 8 carbon atoms, and aromatic monohydric alcohols having 7 to 12 carbon atoms.
(28) The method described in (27) above, wherein the aliphatic primary monohydric alcohol is selected from the group consisting of methanol, ethanol, 1-propanol, 1-butanol, isobutanol, isopentanol, neopentanol, 2-methyl-1-butanol, 1-pentanol, 1-hexanol, and 1-octanol, the aliphatic secondary monohydric alcohol is selected from the group consisting of 2-propanol, 2-butanol, 2-pentanol, 2-hexanol, 2-heptanol, and 2-octanol, the alicyclic monohydric alcohol is selected from the group consisting of cyclopentanol, cyclohexanol, 4-methylcyclohexanol, 3-methylcyclopentanol, and 3-ethylcyclopentanol and the aromatic monohydric alcohol is selected from the group consisting of benzyl alcohol and 2-phenylethylalcohol.
(29) The method described in any one of (22) to (28) above, wherein the intercalation compound in which monohydric alcohol is intercalated between layers of a layered compound comprising vanadium, phosphorus and oxygen as primary components has a structure where a part or the whole of a moiety, POH, present in a layered compound, vanadyl hydrogen phosphatehemihydrate represented by (VO) (HOP)O3. 0.5 H2O, is replaced with a moiety, POR, of phosphoric acid ester of the aliphaticmonohydric alcohol, wherein R represents the residue of the aliphatic monohydric alcohol, and a part or the whole of the H2O present in said layered compound is replaced with the aliphatic monohydric alcohol.
(30) The method described in any one of (22) to (29) above, wherein the reaction pressure is 10 MPa or lower. and
(31) The method described in any one of (22) to (29) above, wherein the reaction pressure is in a range of 0.10 to 4 MPa.
The present inventors have made intensive researched for obtaining a vanadium-phosphorus mixed oxide having a large surface area. As a result, it has been surprisingly found that a vanadium-phosphorus mixed oxide having a remarkably large BET surface area of 80 m2/g, which surface area could not be attained in the conventional methods, can be prepared by heating a specific intercalation compound in the predetermined conditions to accomplish the present invention.
Thus, the present invention is (32) a method of preparing a vanadium-phosphorus mixed oxide by heating an intercalation compound comprising vanadium, phosphorus and oxygen as primary components, characterized in that said intercalation compound is a layered compound comprising vanadium, phosphorus and oxygen as primary components with intercalated aliphatic monohydric alcohol having at least 3 carbon atoms, and said intercalation compound is heated at a temperature in a range of from higher than 250xc2x0 C. to lower than 500xc2x0 C. in an inert gas atmosphere containing oxygen in a concentration, based on the total gas volume, of from 0 to 2.0 vol %.
Preferred embodiments of the aforesaid method are as follows.
(33) The method described in (32) above, wherein the intercalation compound has a structure where a part or the whole of a moiety, POH, present in a layered compound, vanadyl hydrogen phosphate hemihydrate represented by (VO) (HOP)O3. 0.5H2O, is replaced with a moiety, POR, of phosphoric acid ester of the aliphaticmonohydric alcohol having at least 3 carbon atoms, wherein R represents the residue of the aliphatic monohydric alcohol, and a part or the whole of the H2O present in said layered compound is replaced with the aliphatic monohydric alcohol having at least 3 carbon atoms.
(34) The method described in (32) or (33) above, wherein the aliphatic monohydric alcohol has 3 to 8 carbon atoms.
(35) The method described in (34) above, wherein the aliphatic monohydric alcohol is selected from the group consisting of 1-propanol, 1-butanol, isobutanol, 1-pentanol, isopentanol, neopentanol, 2-methyl-1-butanol, 1-hexanol, 1-heptanol, 1-octanol, 2-propanol, 2-butanol, 2-pentanol, 2-hexanol, 2-heptanol, and 2-octanol.
(36) The method described in (34) above, wherein the aliphatic monohydric alcohol is selected from the group consisting of 1-propanol, 1-butanol, 1-octanol and 2-butanol.
(37) The method described in any one of (32) to (36) above, wherein a temperature at which the heating is performed is in a range of from 260xc2x0 C. to 450xc2x0 C.
(38) The method described in any one of (32) to (37) above, wherein the heating is performed in an inert gas atmosphere comprising oxygen in a concentration, based on the total gas volume, of from 0 to 1.5 vol %.
(39) The method described in any one of (32) to (38) above, wherein the inert gas is nitrogen.
(40) The method described in (38) above, wherein the inert gas does not contain oxygen.
The present invention is (41) a vanadium-phosphorus mixed oxide, characterized by a BET specific surface area of at least 80 m2/g.
Preferred embodiments of the aforesaid invention are as follows.
(42) The mixed oxide described in (41) above, wherein a BET specific surface area is in a range of from 80 to 1,000 m2/g.
(43) The mixed oxide described in (41) or (42) above, wherein a total micropore volume is at least 100 mm3/g.
(44) The mixed oxide described in (41) or (42) above, wherein a total micropore volume is in a range of from 100 to 1,000 mm3/g.
(45) The mixed oxide described in any one of (41) to (44) above, wherein a total volume of micropores having a radium smaller than 1 nm is at least 30 mm3/g.
(46) The mixed oxide described in any one of (41) to (45) above, wherein a ratio of a total volume of micropores having a radius of from 1 to 2.3 nm to a total volume of micropores having a radius of from 1 to 100 nm is at least 50%.
(47) The mixed oxide described in any one of (41) to (45) above, wherein a ratio of a total volume of micropores having a radius of from 1 to 2.3 nm to a total volume of micropores having a radius of from 1 to 100 nm is at least 80%.